Three formulations and various consequences of a compactness principle are given. For example it is shown that an infinite partially ordered set has the jump number at most k if and only if none of its finite subsets has the jump number greater than k. Other applications include Ramsey-type results
Coloring linear orders with Rado's partial order
β Scribed by Riccardo Camerlo; Alberto Marcone
- Publisher
- John Wiley and Sons
- Year
- 2007
- Tongue
- English
- Weight
- 146 KB
- Volume
- 53
- Category
- Article
- ISSN
- 0044-3050
No coin nor oath required. For personal study only.
β¦ Synopsis
Abstract
Let βͺ―~R~ be the preorder of embeddability between countable linear orders colored with elements of Rado's partial order (a standard example of a wqo which is not a bqo). We show that βͺ―~R~ has fairly high complexity with respect to Borel reducibility (e.g. if P is a Borel preorder, then P β€~B~ βͺ―~R~), although its exact classification remains open. (Β© 2007 WILEYβVCH Verlag GmbH & Co. KGaA, Weinheim)
π SIMILAR VOLUMES
We show that for a fuzzy partial order R on a ΓΏnite universe , there is a ΓΏnite family of fuzzy linear orders {Li: 16i6k} such that R(x; y) = min{ L i (x; y): 16i6k} for all x and y. This generalizes a well-known result on crisp partial orders, which states that each partial order on a ΓΏnite set is